There are at least two different types of sleep apnea, including obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea (OSA) is caused by an obstruction of the airway. For example, the soft tissue of the airway may collapse thereby obstructing breathing during sleep. Central sleep apnea syndrome (CSAS) is a sleep-related disorder in which the effort to breathe is diminished or absent, typically for 10 to 30 seconds, either intermittently or in cycles and is usually associated with a reduction in blood oxygen saturation. Central sleep apnea is very rare, and typically resolves when obstructions are treated.